Field of the Invention
The general field of this invention is chiropractic adjustment.
Chiropractic adjustment of the spinal vertebrate is commonly made with the use of pressure applied directly to the body with the hands or with the use of a mechanical device. See, for example, U.S. Pat. No. 4,116,235, which discloses a mechanical device for this purpose and discusses in some detail the technique of applying force by application of a thumb thrust.
The force supplied to the patient may vary widely if applied manually or with an instrument. In particular, the energy transmitted to the patient with an instrument depends upon the pressure applied to the patient's body by the instrument under control of the operator. If the contact pressure of the instrument is very low, then very little energy is transferred to the patient. However, as the contact pressure with the patient's bone structure is increased, the energy transferred to the patient increases. This variation in energy constitutes a major problem in obtaining desirable reproducible results. The manually operated units present special difficulties since the operator must typically store energy in an actuator spring by squeezing two projections, while attempting to maintain a constant pressure against the patient.
The primary objective of instrument adjustment is to obtain a desired treatment with the least possible energy transfer to the patient. Instrument adjustment theoretically allows for the precise alignment of force vectors and the application of reproducible minimum force for the required effect. The primary drawback of currently available instruments for spinal adjustment is that the force adjustment mechanisms are crude and vary from instrument to instrument. Usually, no provision is made for varying the energy output of the system when triggering the activator which impacts the adjuster head against the patient. Rather, the releasing mechanism in the prior art devices releases the activator from approximately the same point each time. This causes the energy in the system to be somewhat fixed regardless of what adjustments are made. Additionally, the initial contact force between the activator and patient is solely determined by the force exerted by the operator and therefore may vary over a wide range.